My original question is:
"Must debian-installer use "iso-codes" package when choosing country,
Even though it will hurt some people, like people who living in Taiwan?"
And I think your answer is "YES".

We all consent that to replace "Taiwan" with "Taiwan, Province of China"
is not suitable.

It don't match to the real political situation,
And it will bring a mountain of political disputes.

People who install Debian via debian-installer will find that "Taiwan"
was replaced with "Taiwan, Province of China".

They may not detect immediately that this country code is based on ISO-3166,
But they will think that Debian is discriminating against Taiwan people.
It will not be a very good first impression to Debian users.
And, It is a gross disparagement to Taiwan people.
Thus some of us may refuse to use Debian anymore.
Sorry, but I think it is necessary to repeat again,

I suggest that debian-installer should not use the data form "iso-codes"
package as country code.
We should try to found something else to replace the "iso-codes" package
in debian-installer.